#include<stdio.h>
#include<string.h>

int main(int argc, char* argv[])
{
    if(argc != 2)
    {
        printf("Usage: %s [-a|-b|-c]\n", argv[0]);
    }

	const char *arg = argv[1];
    
    if(strcmp(arg, "-a") == 0)
        printf("功能1\n");
    else if(strcmp(arg, "-b") == 0)
        printf("功能2\n");
    else if(strcmp(arg, "-c") == 0)
        printf("功能3\n");
    else
        printf("Usage: %s [-a|-b|-c]\n", argv[0]);

    return 0;
}
